Download Future wet grasslands: ecological implications of climate change

SPECIAL FEATURE:
WETLANDS AND GLOBAL CLIMATE AND LAND-USE CHANGE
Future wet grasslands: ecological implications of
climate change
Chris B. Joyce, 1,4 Matthew Simpson,2 and Michelle Casanova3
Aquatic Research Centre, School of Environment and Technology, University of Brighton, Brighton, BN11 4NR UK
2
WWT Consulting, Slimbridge, Gloucestershire GL2 7BT UK
3
School of Applied and Biomedical Sciences, Federation University, PO Box 663, Ballarat, Victoria 3353 Australia
1
Abstract. Wet grasslands are threatened by future climate change, yet these are vital ecosystems for both
conservation and agriculture, providing livelihoods for millions of people. These biologically diverse,
transitional wetlands are defined by an abundance of grasses and periodic flooding, and maintained
by regular disturbances such as grazing or cutting. This study summarizes relevant climate change
scenarios projected by the Intergovernmental Panel on Climate Change and identifies implications for
wet grasslands globally and regionally. Climate change is predicted to alter wet grassland hydrology,
especially through warming, seasonal precipitation variability, and the severity of extreme events
such as droughts and floods. Changes in the diversity, composition, and productivity of vegetation
will affect functional and competitive relations between species. Extreme storm or flood events will
favor ruderal plant species able to respond rapidly to environmental change. In some regions, wet
grasslands may dry out during heatwaves and drought. C4 grasses and invasive species could benefit
from warming scenarios, the latter facilitated by disturbances such as droughts, floods, and possibly
wildfires. Agriculture will be affected as forage available for livestock will likely become less reliable,
necessitating adaptations to cutting and grazing regimes by farmers and conservation managers,
and possibly leading to land abandonment. It is recommended that agri-­
environment schemes,
and other policies and practices, are adapted to mitigate climate change, with greater emphasis on
water maintenance, flexible management, monitoring, and restoration of resilient wet grasslands.
Key words: agricultural production; biodiversity; climate extremes; disturbance; drought; ecosystem services;
flooding; mitigation; Special Feature: Wetlands and Global Climate and Land-use Change; wetland.
Citation: Joyce, C. B., M. Simpson, and M. Casanova. 2016. Future wet grasslands: ecological implications of climate change. Ecosystem Health and
Sustainability 2(9):e01240. 10.1002/ehs2.1240
(Brotherton and Joyce 2015). The aims of this study were
to introduce pertinent climate change scenarios and
identify key impacts on wet grasslands globally and regionally, by elucidating the likely ecology of future wet
grasslands under climate change environments, and indicating climate mitigation and adaptation measures.
Wet grasslands can be considered as transitional wetland ecosystems occupying a hydrological gradient between permanently inundated wetlands, such as reed
swamps, and dry grasslands in which water is insufficient to define the vegetation. Many are “seminatural”,
formed by drainage of other wetland types or forest
clearance on floodplains but still largely comprised of
characteristic native plant species (Dixon et al. 2014).
Typically, they are located in lowland landscapes (e.g.,
<1,000 m in elevation; Table 1). These wetlands are found
on peat, alluvial, or mineral substrates and may be
known regionally or locally by a variety of terms (Table 1;
see Fig. 1 for examples). However, all wet grasslands are
Introduction
Wet grasslands are biologically diverse wetlands dependent upon hydrological regime and vegetation management for their particular characteristics, but the
sustainability of both these key controls is threatened by
climate change. These wetlands are defined by an abundance of grasses (or sedges), as well as periodic flooding
with fresh or brackish water, or a high water table for
some of the year, sufficient to influence the vegetation
(Joyce and Wade 1998). Climate change, which is manifested particularly through increased temperature, variations in precipitation, and extreme events, has the
potential to severely disrupt nature conservation and agricultural management regimes in wet grasslands,
thereby impacting upon human livelihoods and society
Manuscript received 25 November 2015; revised 23 June 2016;
­accepted 27 June 2016.
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E-mail: [email protected]
Ecosystem Health and Sustainability
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JOYCE ET AL.
Special Feature: Wetlands and global climate and land-use change
Table 1. Subcategories of wet grassland landscapes, examples of terms used to describe types, and sources of disturbance.
Landscape setting
Floodplain
Coastal
Lacustrine
Mire
Depressional
Human
Examples of types
Typical disturbance
Riparian, alluvial, flood pulse, monsoonal, flood meadow
Seashore, grazing marsh, deltaic marsh
Inundation
Fen meadow
Dambo†, wet prairie, wet steppe, wet savanna
Washland, polder‡, water meadow
Flooding, cutting, fire
Grazing, inundation
Flooding, grazing
Cutting
Grazing, fire
Inundation, grazing
Notes: See Fig. 1 for images of example grasslands.
†Seasonally waterlogged, grassy depressions bordering headwaters in central and southern Africa.
‡Low-­lying wet grasslands claimed from the sea or other bodies of water.
maintained by disturbance (Table 1), which prevents
­establishment by trees or shrubs. Often, disturbance is
imposed by flooding and vegetation management as
part of an agricultural system that utilizes primary production to support d
­ omestic herbivores directly through
either grazing (pastures) or hay fodder (meadows; Joyce
and Wade 1998). Burning is also practiced on some wet
grasslands, such as in tropical regions, often to remove
coarse or woody vegetation and maintain soil productivity (Woodward 2003). Natural wet grasslands also
exist, usually subject to disturbance by flooding, waterlogging, or herbivory, which constrain colonization by
shrubs and trees. Savanna-­
type wetlands, which particularly occur in the tropics, support scattered trees but
retain the dominant cover of grass or grass-­like species.
Thus, wet grasslands can appear to represent a heterogeneous ­resource, with different types located in a variety
of ­landscapes, but all have a common eco-­hydrological
template ­defined by regular disturbance (Table 1). These
wetlands consequently show similarities in their vegetation structure and composition (Fig. 1) and in the management of their valuable attributes. Such similarities
provide a unifying basis on which to evaluate the likely
impacts of climate change on wet grasslands.
Wet grasslands can ameliorate the effects of climate
change through their provision of ecosystem services. These wetlands regulate surface runoff, attenuate
flooding, recharge aquifers, and provide fresh water,
as important components of the water cycle (Joyce and
Wade 1998). Wet grasslands contribute to carbon storage
and sequestration (Fidelis et al. 2013), mostly in belowground biomass, especially in some tropical grasslands
and peat-­
based systems. Coastal wet grasslands provide protection against storms and flooding (Gedan
et al. 2011, Ward et al. 2015). The productivity of wet
grasslands is harnessed by humans to yield forage for
livestock, providing a livelihood for millions of people.
Some species provide unique services, such as the golden grass (Syngonanthus nitens) of the Jalapão region of
Brazil, which is harvested to make jewelry and house
decorations for sale by local people (Schmidt et al. 2007).
Climate change may have particularly important consequences for wet grassland stakeholders, because climate
events such as flooding or drought can delay or alter vital management activities such as hay cutting, livestock
Ecosystem Health and Sustainability
grazing, or burning, leading to loss of income or nature
conservation benefits.
Wet grasslands are not often specified in wetland
inventories or reports (e.g., Russi et al. 2013) and are
overlooked in the climate change literature, including
assessments by the Intergovernmental Panel on Climate
Change (IPCC). However, these wetlands provide an
­interesting case for elucidating climate change effects,
­being widely distributed, geographically varied, but with
key hydrological, vegetation, and management features
in common. These wetlands may be particularly sensitive to climate change as they are ecotonal, transitional
between terrestrial and aquatic systems, and maintained
in a dynamic equilibrium by disturbance yet responsive
to hydrological fluctuations (Toogood et al. 2008, Berg
et al. 2012). Moreover, wet grasslands show limited topographic variation (Ward et al. 2013) so that species may
lack refuges from floods or climate warming. In addition, many remaining wet grasslands are fragmented or
isolated (Casanova 2012) and the characteristic and rare
plant species of diverse communities (e.g., orchids) tend
to lack mobility due to low dispersal rates (Joyce 2014).
Thus, wet grasslands might provide an early warning of
climate change impacts upon ecology, especially as diverse systems can allow small or rapid responses to be
discriminated (Joyce 2001).
This review introduces the main climate change scenarios that will affect future wet grasslands and then
identifies key impacts related to hydrological change,
plant community responses, and human management.
The review also proposes mitigation and adaptation approaches to climate change for wet grasslands.
Climate Change Scenarios
Climate change predictions made by IPCC (2014) and
others are seldom generated specifically for wetlands.
Climate change incorporates the global temperature increase and other longer-­term climatic changes related to
increases in greenhouse gases in the atmosphere, and also
short-­term extreme events. Although not developed for
wet grasslands, IPCC (2014) predictions for climate
change until 2100 can be summarized into four main
drivers of hydrological and vegetation change in these
wetlands: (1) an increase in temperature, probably
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Fig. 1. Examples of wet grassland types. (a) Floodplain grassland, England; (b) fen meadows, Biebrza, Poland; (c) Baltic coastal
grassland, Estonia; (d) wet prairie, Indiana, United States; (e) depressional grassland, Victoria, Australia; (f) tropical wet grassland
landscape, Marajo, Brazil.
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affecting high latitudes more than tropical and subtropical wetlands, reducing snow and ice cover; (2) changes in
total precipitation and precipitation seasonality and patterns, including snow cover and melt; (3) a rise in sea
level impacting coastal wetlands; and (4) an increase in
climate variability and extreme events, notably intense
precipitation and extreme temperatures with consequent
heatwaves, storms, drought, and floods. Contrasts between wet and dry regions, and wet and dry seasons, are
expected to increase. Monsoons are likely to intensify.
Wet grasslands could also be affected by more wildfires,
especially if they dry out at the surface or if biomass has
accumulated, and altered salinity, particularly due to saltwater intrusion into freshwater systems. Moreover, an
accumulation of greenhouse gases, especially carbon dioxide (CO2), will affect soil biogeochemistry, plant production, and species competitive relationships. Interactive
effects are also likely to exacerbate climate change, such
as droughts concentrating salinity at the soil surface to
create particularly stressful conditions for vegetation
(Eliáš et al. 2013). Climate change and the rate of change
are likely to affect social, economic, and agricultural functioning (IPCC 2007), and cause environmental concerns
such as biodiversity and habitat loss (McCarty 2001).
The climate change scenarios predicted by IPCC (2014)
include extreme episodes driven by high temperatures
and/or intense precipitation, yielding events such as
droughts or floods. Smith (2011) describes extreme climate events as those defined by great magnitude over
short temporal scales that may cause profound ecosystem responses, often disproportionately greater than
those predicted under steady change scenarios. Extreme
events are likely to be particularly relevant to wet grasslands as these will disrupt hydrological regimes and
vegetation, with consequences for human management.
Grasslands on floodplains or the coast may be especially
susceptible to flooding and storms, and peat-­based grasslands are vulnerable to drought. From an ecological perspective, climate events can be considered a disturbance
that impacts plant functioning, biodiversity, and ecosystem processes (Brotherton and Joyce 2015). Globally, extreme weather or climate events are expected to become
more frequent and increase in intensity and duration
in response to the changing climate (Tebaldi et al. 2006,
IPCC 2012). Already, heatwaves have become more frequent in Europe, Asia, and Australia and extreme precipitation events have increased in North America and
Europe (IPCC 2013).
wetland types are generally not well understood (Erwin
2009). Wet grasslands, in common with other wetlands,
are located across numerous biomes and there is no single climatic template. Regional predictions of the consequences of climate change are complicated by the
distribution of wet grasslands on land masses in different
climatic zones and constrained by a lack of data availability (Junk et al. 2013). Nevertheless, the potentially widespread and severe effects of climate change on wet
grasslands can be summarized by considering predicted
scenarios and identifying types likely to be affected
(Table 2). This synthesis indicates that wet grasslands located in tundra or boreal climates are likely to be affected
by less ice and snow cover. Temperate humid wet grasslands could be subject to increased precipitation and sea
level rise, the latter leading to coastal squeeze. More intense precipitation and floods could impact temperate
continental or semiarid wet grasslands, which could also
be affected by fires, heatwaves, and droughts, with reduced river flows. Mediterranean wetlands, and those
located in desert regions, could be increasingly prone to
drought and fires in a climate change future. Tropical humid wet grasslands could experience more intense rainfall and flooding, as well as sea level rise in coastal
marshes and meadows. It is expected that greater rainy
and dry season variations will influence wet grasslands in
tropical semiarid areas, with intensification of the monsoon, heatwaves, and droughts. The case of South
America alone reinforces the multiple suite of threats that
wet grasslands face. Melting snow and ice in the glaciers
of Patagonia and the Andes will alter surface runoff into
interior wetlands, sea level rise of between 20 and 60 cm
will destroy coastal marshes, and an increase in extreme
events, such as storms, floods, and droughts, will affect
biodiversity in wet grasslands (after Junk et al. 2013).
The potential impacts of climate change on wet grasslands are complex and severely damaging (Table 2);
however, some regions may benefit from enhanced wet
grassland creation and productivity. For example, the
Hadley Centre’s climate and vegetation model predicts
conversion of Amazon rain forest to cerrado (savanna-­
type) vegetation from 2050 to 2100 (Jenkins et al. 2005).
Also, warmer and wetter conditions will enhance soil
water availability and primary productivity in wet prairies in some eastern parts of the northern plains of the
United States and southern Canada (Polley et al. 2013).
Greater water availability in some regions where precipitation is forecast to increase (e.g., northern Europe,
Table 2) may also offer opportunities to restore or create
new wet grasslands, possibly from intensively managed
grasslands or croplands.
Climate Change Impacts on Wet Grassland
Ecology
Climate change impacts on wet grasslands will be manifested through hydrological and vegetation changes, and
these will have important implications for agricultural
management. However, it should be noted that projected
effects of climate change on wet grasslands and other
Ecosystem Health and Sustainability
Hydrological changes
Climate change will have its most pronounced effects on
wet grasslands through alterations in hydrological regimes, especially the nature and variability of flooding
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Table 2. Regional climate scenarios (after Ramsar 2002; IPCC 2013, 2014), stressors, and examples of wet grassland types likely
to be impacted.
Scenario
Europe
Increased precipitation in northern
Europe
Decreased precipitation in southern
Europe
Decreased snow cover and more rapid
snow melt
More frequent heatwaves
Wildfires
Sea level rise
Asia
Earlier loss of ice cover and reduced
semipermanent permafrost
Stressors
Increased fresh water in brackish or saline
waters
Drought
Seashore grasslands in Baltic coastal
wetlands
Mediterranean grasslands
Reduced water availability and altered
flood pulse
Heat stress and drought
Central European floodplain grasslands
downstream of mountains
Continental flood meadows, for example, Rhine floodplain, Germany
Steppe wet grasslands
Grazing marshes along the North Sea;
Baltic and Mediterranean grasslands
Fire damage
Salt water intrusion, sedimentation,
storms, and erosion
Invasion of southern species northward
and spread of shrubs
More frequent and intense rainfall
events in south Asia
Flooding
More frequent heatwaves
Heat stress and drought
Sea level rise
Erosion and salt water intrusion
Intensification of the monsoon
Extreme floods and storm damage
Decreased snow cover and therefore
melt in the Himalayas
Decreased water availability and more
seasonal river flow and groundwater
recharge
North America
Reduced snow and ice in mountains and
in northern regions, earlier snow melt
and reduced permafrost in the north
More frequent, intense floods
More frequent heatwaves and protracted drought (megadrought)
Sea level rise
Wildfires
Increased severe rain events
Reduced river flow in continental rivers
due to more evaporation, less rain,
and more abstraction by humans
Neotropics
Reduced snow and ice in mountains
“Tundra” wet grasslands of the
Himalayas and in Siberia; semitundra
wet grasslands, for example, Sanjiang
Plain, northeast China
Seasonal floodplain grasslands, for example, Mekong and Yangtze; seasonal marshes in Heilongjiang
Province, northeast China
Central Asian steppe grasslands of the
Dauria ecoregion; seasonal monsoonal marshes on floodplains of the
Ganges, Indus, and Brahmaputra
Deltaic marshes, for example, Mekong
and Yangtze; Yellow Sea saline meadows, China
Coastal grasslands behind barrier islands,
for example, east coast of Sri Lanka;
wet–dry floodplain grasslands of the
Ganges, Indus, and Brahmaputra
Groundwater-­fed grasslands of the
Himalayan terai
Altered surface and groundwater flow;
and less ice and flooding in winter
Wet prairie, prairie fen, and riparian
grasslands in northwest America
Extreme flooding and vegetation change
to flood-­tolerant species
Heat stress, drought, and summer drying
Wet grasslands in the prairie pothole
region
Continental depressional grasslands and
prairie potholes, for example, reduced breeding wildfowl habitat
Atlantic and Gulf coasts of America
Wet rangelands, for example, expansion
of invasive species
Riparian grasslands
Erosion and saline intrusion
Fire damage, smouldering peat fires, and
peat loss
Increased suspended sediments and
diffuse pollutants in rivers
Penetration of coastal salt water wedge
further inland
Altered surface and groundwater flow,
and less ice and flooding
More frequent and intense precipitation
events in the tropics
Flash flooding and erosion along
floodplains
More frequent floods
Extreme flooding and vegetation change
More frequent drought
Atypical seasonal drying and loss of
biodiversity
Ecosystem Health and Sustainability
Examples of wet grasslands impacted
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Freshwater coastal grassland and floating grasslands, for example,
Mississippi River lower delta and
northern Gulf Coast
Wet paramo of Central and South
America; Andean grasslands; Beni
savannas of the Amazon basin, Bolivia
Flood pulse grasslands; tropical wet–dry
wetlands, for example, Palo Verde in
western Costa Rica
River floodplain ecosystems, for example, Pantanal, Brazil
Central Chilean grasslands; savanna wet
grasslands, Gran Sabana, Venezuela
(continued)
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Table 2. (continued)
Scenario
Stressors
Wildfires
Fire damage and shift toward fire-­
tolerant species
Greater rainy and dry season variations
Altered fire-­flood patterns and loss of
biodiversity
Food production, water availability for
humans, and livelihoods at risk
Africa
More frequent intense precipitation
events in the tropics and enhanced
monsoons in west Africa
Forage quality and quantity
Flooding and erosion
Droughts
Drought stress and drying
Wildfires
Greater rainy and dry season variations
Fire damage
Biodiversity loss and invasion by trees in
the dry season
Reduced runoff and discharge
Enhanced evaporation loss from rivers
and lakes
Food production and livelihoods at risk
Oceania
Reduced snow and ice, and fewer frosts
Biomass and forage quality and quantity
Altered seasonal river flows
More hot days and warm periods
Heatwaves and drought
Less rainfall in the cool season, especially
in southern Australia
Sea level rise and increased height of
extreme sea level events
Reduced water supply
Increased intensity of El Niño and
extreme rainfall events
Flooding
Increased rainfall in northern Australia
and southern Papua New Guinea
Harsher fire-­weather climate and
contracting winter wet season
Land-­use change through water storage,
dam building, and drainage
Longer fire season and greater fire
frequency
Saline intrusion and habitat squeeze near
the coast
and the severity of extreme events. Key relationships are
those involving (1) reduced precipitation and increased
evapotranspiration under warming scenarios, leading to
drying of wetlands; (2) altered precipitation patterns affecting seasonal water availability, snow melt, and the
timing and extent of flooding; (3) sea level rise, storminess, and saline intrusion in coastal grasslands; and (4)
intense rainfall events that generate extreme flooding.
The following sections on climate warming, altered precipitation, sea level rise, and extreme events discuss the
possible effects of these climate change impacts on wet
grasslands and their ecology.
Wet savanna grasslands, North
Rupununi, Guyana; Amazonian
grasslands
Llanos esteros grasslands, Venezuela;
seasonally flooded Campos, Brazilian
Parana
Rangelands; natural (hay) grasslands;
Llanos grasslands, Venezuela
Flood pulse grasslands and savanna, for
example, Niger and Zambezi floodplains; Tana River Delta, Kenya; Nile
Delta floodplain grasslands
Dambos in southern Africa; Okavango
Delta, Botswana
Mara River basin savanna grasslands
Seasonally flooded grasslands of the
Zambezi, Zambia
Okavango Delta; Lake Victoria papyrus
grasslands
Hand-­gathered cattle forage; Mara River
basin savanna grasslands
Headwater valley grasslands, New
Zealand
Seasonal wet grasslands become
intermittent
Swampy meadows, for example, southeast Australia
Coastal freshwater floodplains in
Australia and New Zealand; dunal
meadows; Murray River grasslands
Murray River mudgrass grasslands; wet–
dry grasslands of the Northwest
Territory
Wet grasslands converted to palm oil
cultivation or crops
Productive grasslands damaged
et al. 2009, Thompson et al. 2009). For example, important
herbaceous wetlands in East China could be threatened
as rainfall decreases but evapotranspiration increases
(Ramsar 2002). A model of floodplain dynamics under
different climate scenarios predicts that the number of
shallow flood events in the UK would decrease by up to
90% because of reductions in available water (Thompson
et al. 2009). Therefore, some wet grassland species in
England are expected to migrate northwards as a result of
increased temperatures reducing water tables (Dawson
et al. 2003), potentially resulting in the loss of dominant
functional species, which may affect ecosystem processes.
In western Victoria in Australia, rainfall is predicted to
decrease and temperatures increase, leading to overall
drier grassy wetlands that inundate less frequently, and
for shorter periods. Historical average inundation was six
or seven years of flooding in every decade (Casanova and
Powling 2014), but in the last two decades these wetlands
have only been inundated approximately four times per
Climate warming
A combination of higher temperatures and decreasing
rainfall predicted under many climate change scenarios is
likely to exacerbate deficits in water budgets for many
temperate wet grasslands through increased evaporation
and evapotranspiration (Dawson et al. 2003, Acreman
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Examples of wet grasslands impacted
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decade. One consequence of fewer filling events has been
to encourage a change in land use from grazing to cropping, which had significant effects on the biodiversity
and ecological integrity of these wet grasslands (Casanova
2012). Reduced water supply to wet grasslands could also
initiate a negative feedback loop in which these wetlands
would be unable to recover, favoring a more terrestrial
community (Čížková et al. 2013) and leading to changes
in nutrient cycling, decomposition, soil microbes, and
primary production (Öquist and Svensson 1996). In some
regions, such as southeast Europe, higher temperatures
and increased aridity will lead to wet grasslands becoming subhalophytic where evaporation of water causes a
high concentration of salts in the soil (Eliáš et al. 2013)
and some Mediterranean wet grasslands could even disappear. Under drying climate scenarios, conditions will
become suboptimal for wading birds, because their distribution is strongly related to surface wetness (Eglington
et al. 2008).
Increased summer temperatures, longer dry seasons,
and more extreme temperatures are predicted to increase
the incidence of wildfires in many regions (Table 2). The
extent to which fires will impact wet grasslands is debatable because many will already be damaged by drought,
and burning can maintain diversity in some wetlands
(Middleton 2002). However, predictions for greater seasonal climate variability suggest that wetter winters may
allow intermittent wetlands to persist into the summer
rather than dying back in spring, so that droughts may
then make them vulnerable to wildfires. The extensive
wet campos meadows of the Brazilian Parana are characterized by a diversity of herbaceous species and a highly
seasonal tropical climate that leads to massive flooding
and fires (Dixon et al. 2014). Greater seasonal contrasts
may alter this disturbance regime and induce vegetation
change, especially if more fires and less flooding encourage savanna habitat. Thus, prolonged dry seasons,
especially following wet years when biomass has accumulated, could lead to a greater risk of severe fires in
some tropical wet grasslands (Fidelis et al. 2013).
such as riparian meadows and floodplain grasslands,
will be susceptible to altered precipitation patterns if surface water is a dominant supply (Öquist and Svensson
1996, Brinson and Malvárez 2002).
Seasonal climate changes likely to affect some wet grasslands include the extent and duration of snow or ice cover
(Table 2). For example, spring snow cover in the Northern
Hemisphere is likely to decrease by up to 25% by the end
of the 21st century (IPCC 2014), so that many boreal and
submontane systems will have reduced or no snow in winter. Snow and (sea) ice is a controlling factor for these wet
grasslands (Kont et al. 2007), influencing soil biogeochemistry, plant ecology, and grazing management. Higher
snow lines in both Australia and New Zealand are likely to impact on the seasonal variation in river flow. Even
if precipitation does not decrease, precipitation as rain is
likely to contribute to river flow immediately, rather than
seasonally as it does when it falls as snow and melts in the
spring. Reduced snow cover or earlier melt will affect the
flood pulse in downstream wet grasslands, diminishing
its influence or forcing it earlier, with attendant negative
consequences for the plants, animals, and people that depend upon predictable flooding. The Beni wet savannas
of the Amazon basin in Bolivia typically have a relief of
2–6 m and 50–60% of the land floods each year between
December and May as a result of high rainfall and snowmelt in the Andes (Dixon et al. 2014). Disruption to this
hydrological regime will have substantial consequences
for biological diversity, as the Beni wetlands are a refuge
and wintering ground for many migrant waterfowl.
Sea level rise
It is estimated that 20% of coastal wetlands, which includes brackish wet grasslands, could be lost in Europe
due to sea level rise (Russi et al. 2013) if they are constrained on their landward side, or starved of sediment.
Wet grasslands along seas with low tidal ranges, such as
the Baltic and Mediterranean, are most threatened by future sea level rise because these tend to have low relief
and their constituent species are adapted to relatively
stable water regimes with irregular flooding (Ward et al.
2014, 2015). Moreover, the Baltic countries of Europe will
experience more ice-­free seas, which may reduce protection from coastal erosion, while strong storms and surges
will potentially deposit sediment further inland on depositional coasts (Ward et al. 2014). If this is the case, wetlands could prograde and lower shore wet grasslands
close to the sea could benefit, especially if sea level rise is
compensated by isostatic uplift (Ward et al. 2015).
However, sea level rise could lead to sea shore grasslands being replaced by swamp or land recession around
shallow bays, where extensive and important wet grassland landscapes currently exist (Kont et al. 2007). The
saline meadows inland of the Yellow Sea, China, which
are flooded at high tide (Dixon et al. 2014), could also be
threatened if salinity patterns are altered or the grasslands are unable to migrate inland. In Mediterranean
Altered precipitation including snow
Wet grasslands in transitional climates or with a low hydrological buffer capacity, such as those impounded by
embankments or with small catchments, are likely to be
especially sensitive to changed precipitation patterns.
For example, prairie pothole wetlands in North America
could be highly impacted by seasonal rainfall shifts during climate change due to their location between the wet
east and arid west of the continent (Junk et al. 2013,
Mallakpour and Villarini 2015). Moreover, wet grasslands can respond more markedly to precipitation increases than drier grasslands; Guo et al. (2012) found that
humid meadow steppe productivity in China increased
linearly with greater mean annual precipitation, and
more so than drier steppe grasslands. Even river-­fed wet
grasslands that are not directly dependent upon rainfall,
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countries, saline intrusion can fundamentally alter the
vegetation and related biodiversity of wet grasslands fed
by fresh groundwater, especially near the coast but also
much further inland (Rey Benayas et al. 1998). Coastal
freshwater floodplains in Australasia (particularly in
southern Australia, Kakadu in northern Australia, and
New Zealand) and Asia (such as the Mekong delta) are
likely to experience major changes as sea level rise will
inundate near-­
coast wetlands and estuarine systems.
The grassy Kakadu wetlands in northern Australia will
be squeezed between the sea and the Arnhemland escarpment (Eliot et al. 1999). In southern Australia, sea
level rise, coupled with lower rainfall and less runoff in
rivers and onto floodplains, will constrain freshwater
wet grasslands between encroaching estuarine conditions and existing agricultural or urban land use. In general, coastal regions are highly utilized for urban
development, aquaculture, and farming. It is unlikely
that areas used in this way will be converted or managed
to mitigate wetland loss.
with belowground storage. In contrast, an inundation
community intensely disturbed by flooding supported limited species richness and ruderal strategists with
short life cycles and high potential growth rate (e.g., via
rhizomes or stolons). The latter environment offers an insight into possible future wet grassland scenarios under
climate extremes, characterized by greater variability and
dynamism, and potentially more reliance on seeds and
propagules (Casanova 2015). Such grasslands, consisting
of fast-­growing, short-­lived species, have responded rapidly to experimental climate change treatments (Zavaleta
et al. 2003) and are likely to be sensitive to climate events.
Further evidence from Baltic coastal landscapes suggests
that wet grasslands from dynamic hydrological environments respond rapidly to environmental change while
diverse communities with more stable hydroperiods
show resistance to perturbation (Berg et al. 2012).
The effects of heatwaves and drought on wet grasslands are not known, and will vary due to differences in
soil permeability affecting moisture retention. However,
as these are typically only seasonally inundated or saturated wetlands, some wet grasslands may become
intermittent or even dry out completely, such as in southern Europe and southern Australia. Moreover, lower
groundwater levels may increase the availability of nitrogen and phosphorus in the soil, leading to eutrophication and acidification (Van der Hoek and Braakhekke
1998). In theory, drought events could act as a disturbance and increase diversity by reducing competition in
wet grasslands, but this is likely to be beneficial only in
abandoned meadows and pastures, and probably offset
by the damaging impacts of drought stress. Drought effects are likely to be more severe if grazing or other vegetation management continues, as this exacerbates loss of
species and cover in grasslands (Archibold 1995). There
is evidence from other vegetation types, such as woodland, that changes following drought and other extreme
climate events may be irreversible (Allen and Breshears
1998, Holmgren et al. 2001).
Extreme climate events
Although wet grassland species possess various attributes to survive flooding (Blom and Voesenek 1996), field
studies have indicated that extreme precipitation and
flood events can have profound impacts on community
composition. Less flood-­tolerant plant species can show
reduced distribution for many years following extreme
flooding, in contrast to more flood-­tolerant riparian species (Vervuren et al. 2003). Although vegetation abundance on floodplains does not necessarily decrease after
extreme flooding (Sparks et al. 1990), diversity and species turnover can be immediately affected (Ilg et al. 2008).
For wet grasslands, it seems that the magnitude and duration of extreme flood events will both be critical, potentially prompting more rapid responses than those
reported from some terrestrial communities (Toogood
and Joyce 2009). Berg et al. (2012) observed that winter
storms and subsequent flooding affected Baltic coastal
wet grassland communities much more than cutting
management, including changing species dominance.
Unseasonal inundation, such as summer flooding in
temperate wet grasslands, is particularly problematic because it can induce plant community, soil nutrient, and
biodiversity impacts, including damage to the terrestrial
invertebrate fauna (Burgess et al. 1990, Benstead et al.
1999, Antheunisse and Verhoeven 2008). Moreover, prolonged flooding can kill or expel invertebrates in the soil
or litter that are not adapted to extended submersion,
with potentially harmful consequences for the wading
birds that feed upon them (Ausden et al. 2001).
From an ecological perspective, extreme storm or flood
events represent intense disturbance. Joyce (1998) compared two floodplain grassland plant communities in the
UK with contrasting responses to disturbance. A flood-­
meadow community with a stable disturbance regime
was characterized by competitive, stress-­tolerant species
Ecosystem Health and Sustainability
Plant community responses
For wet grasslands, climate change may be expected to
affect community composition by modifying dominant
plant traits (i.e., adaptations to particular environmental
conditions), competition, distribution, and diversity
(Easterling et al. 2000, McCarty 2001, Reyer et al. 2013).
Climate change could also influence communities
through increased CO2 uptake, which critically influences biomass development and grassland productivity.
The following sections examine possible consequences
of climate change on vegetation by focusing upon both
community composition and production.
Community composition
Plant responses to climate change are complex and will
modify competitive relations between species, which
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Special Feature: Wetlands and global climate and land-use change
may be crucial in wet grasslands where a diversity of
perennial species coexist. For example, drier soils will reduce waterlogging and anoxia stress, favoring competitive species such as widespread grasses at the expense of
more specialized, often rare wetland species. Elevated
atmospheric CO2 will directly stimulate photosynthesis
and plant growth (the “fertilization effect”). Enhanced
CO2 could reduce the negative effects of drying or even
drought (Soussana and Lüscher 2007) in a warmer climate by increasing plant water-­use efficiency (Polley
et al. 2013), although this crucially depends upon soil
water availability in wet grasslands. Sajna et al. (2013)
found that a wetland sedge (Carex rostrata) increased biomass under conditions of enhanced CO2 and elevated
soil water content in a central European wet meadow,
perhaps because the species is well adapted to waterlogged soil and hypoxia. Elevated CO2 could reduce diversity in wet grasslands if increased CO2 delays
senescence of the dominant plant canopy at the end of
the growing season, constraining the window of light
availability for late-­flowering and small-­statured species
(Zavaleta et al. 2003).
Climate change could favor particular plant adaptations, traits, or functional groups over others, such
as the ability to spread laterally and rapidly using stolons following gap creation by storms (Berg et al. 2012).
Examples of informative functional groups in wet grasslands include legumes, herbs or forbs (i.e., all nonwoody
flowering species not including grasses), competitors
and ruderals, and annuals and perennials (Toogood et al.
2008, Toogood and Joyce 2009). Legumes, for example,
can facilitate the flowering of other grassland species
under both extreme drought and precipitation (Jentsch
et al. 2009). Forbs might be particularly sensitive to climate changes (Zavaleta et al. 2003) and often comprise
most of the plant diversity in wet grasslands. Studies on
keystone components of wet grassland communities,
such as dominant grasses, robust sedges, or herbs, or
rare species of nature conservation importance, would
provide valuable information on community functioning
and management in the face of climate change.
The distribution of wet grassland plant species will
likely undergo contraction at the margins of their climate range due to limited dispersal opportunities and/or
the pace of climate change. In Great Britain and Ireland,
for example, Berry et al. (2002) suggested that species at
the southern limit of their distribution will be reduced
by climate warming, such as flat sedge (Blysmus rufus),
which could be progressively lost from Wales, northern
England, and Scotland. However, species at their northern range margin could expand their distribution northwards, including greater burnet (Sanguisorba officinalis),
a dominant forb in the rare English flood-­meadow plant
community. Some wet grassland species are expected
to migrate northwards as a result of increased temperatures reducing water tables (Dawson et al. 2003), perhaps
into other wetlands. Greater water deficits in temperate
regions could lead to reduced climate suitability for various peat-­based wet grassland plant species in particular,
because these tend to have narrow hydrological niches
(Newbold and Mountford 1997).
C4 grasses could benefit under warming scenarios
because these grow at higher temperatures (optimum
30–35°C), absorb CO2 more efficiently, and have greater water-­use efficiency than C3 grasses (t’ Mannetje
2007). The distribution of C4 species is related to winter temperatures because these are impaired by the
cold (Archibold 1995). Thus, warmer winters may be
especially important for their expansion into and within temperate wet grasslands. C4 grasses also have a
greater production capacity than C3 grasses. However,
the forage value is less because of a lower proportion
of digestible tissues, leading to negative implications for
agricultural management and livelihoods should C4 species expand in wet grasslands. Increases in climate extremes may suppress C3 species and promote C4 species,
including weeds, due to faster migration rates, greater
seed production, and rapid maturity (White et al. 2001).
C4 grass species that could conceivably spread within
wet grasslands in a climate change future include many
within the Panicoideae subfamily, which prefer humid,
wet environments. For example, Chrysopogon gryllus
and Dichanthium ischaemum are already widespread in
humid central and southern Europe, and could increase
in abundance (t’ Mannetje 2007) and move northwards.
Bermuda grass (Cynodon dactylon), which like many C4
grasses is a common constituent of many tropical wet
grasslands, could also be favored by climate change.
This species is already a widespread invader of temperate grasslands and coexists with C3 species as a non-­
native in Pampean grasslands in Argentina (Omacini
et al. 1995). Other traits that may be favored in the future
include those related to fire tolerance, such as storing energy in roots to aid recovery, if the incidence of wildfires
increases as predicted for some wet grassland systems.
Fires in winter or early spring encourage C4 grasses at
the expense of C3 grasses in some South American grasslands (Overbeck et al. 2007).
Droughts, storms, floods, and fires tend to open the
vegetation canopy and create gaps, suitable for colonization by non-­native plant species and those with invasive
traits. Wet grasslands are not especially prone to invasion, but there are a number of examples where invasion
has followed deliberate introduction or disturbance, often through farming activities such as intensive cattle
grazing. The flood-­tolerant koronivia grass (Brachiaria
humidicola) was introduced from Africa into the Pantanal
of South America where ranchers have helped distribute it across the region because they believe it can improve pasture quality (Junk et al. 2013). Similarly, the
Pampean grasslands of Argentina contain numerous
exotic plant species, especially grasses, playing a defining role in their vegetation dynamics (Facelli et al. 1989,
Omacini et al. 1995). Rychnovská et al. (1994) report that
Ecosystem Health and Sustainability
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Special Feature: Wetlands and global climate and land-use change
an abandoned meadow in central Europe was infested
by the weed Epilobium ciliatum after mowing opened
the canopy to colonization. In North America, problems
with invasive species in restored wet grasslands are common, especially sedge meadows and wet prairies where
rehabilitation is severely constrained by the dominance
of aggressive species such as reed canary grass (Phalaris
arundinacea), which preempts the establishment of native
vegetation (Adams and Galatowitsch 2006). Thus, the
increasing frequency and magnitude of extreme events
that typify climate change scenarios are likely to provide
greater opportunities for invasive species to colonize and
dominate wet grasslands in the future.
people who use their agricultural and other ecosystem
services. The following section highlights interactions
between climate change and humans in wet grasslands,
particularly insecurities over agricultural grassland productivity and management.
Climate change will fundamentally affect the availability of biomass for forage in wet grasslands. For example,
altered river hydrology will affect the quality of grazing of the Sudd grasslands in the Sahel, Africa, and the
number of cattle that can be supported, as well as other
ecosystem services such as fish production (Junk et al.
2013). Productive grasslands in northern China have less
annual available herbage and carrying capacity for livestock under the warmer and drier climate of recent decProduction
ades (Qian et al. 2012). The annual hay yield decreased
Primary productivity is dependent upon an interacting by up to 50% under reduced experimental precipitation
suite of climatic factors, including precipitation, tempera- in floodplain meadows along the Rhine River, Germany,
ture, and carbon and nutrient availability, so the precise due to less productivity in the second harvest (Ludewig
outcome of climate change for wet grassland regions is et al. 2015). Also, elevated atmospheric CO2 concentradifficult to determine. Biomass accumulation is driven by tion may alter the feeding value of forage, for example,
seasonality so climate changes will affect carbon stocks by affecting the crude protein content and C:N ratio
and storage, such as in the dry season in tropical wet (Soussana and Lüscher 2007). Even a relatively simple
grasslands. In markedly seasonal wet grassland ecosys- projection of warmer and wetter springs would produce
tems, climate change could alter biomass provision as increased biomass early in the growing season while driplants allocate resources below ground during the dry er falls would reduce late season biomass (Ma et al. 2010),
season and reallocate resources above ground to produce necessitating adaptations by farmers and conservation
new leaves, shoots, and reproductive organs when the managers in respect to (earlier) cutting dates and (earlirainy season begins (Fidelis et al. 2013). Warmer climates er, lighter) grazing regimes. Ironically, this early-­season
will generally extend the growing season and enhance scenario is reminiscent of the traditional water meadow
productivity, as higher temperatures accelerate plant system, which has largely fallen out of favor, in which
growth, especially of grasses (Kudernatsch et al. 2008). farmers utilized river water to irrigate their grassland in
For example, agricultural productivity could be increased spring using a network of drainage channels to provide
in northern Asia (Ramsar 2002) and in northern Europe an “early bite” for livestock (Sheail 1971).
due to rises in temperature and CO2 (t’ Mannetje 2007).
A probable outcome of climate change is that agriWarming could also accelerate senescence of the early-­ cultural production in many regions, such as southern
season grass canopy, increasing subsequent resource Europe, may become less secure because of water shortavailability (Zavaleta et al. 2003). Increased annual pre- ages (t’ Mannetje 2007) and extreme events. In Europe,
intensity agricultural management has been praccipitation can also enhance grassland productivity (Guo low-­
et al. 2012) although wet grasslands in humid regions ticed in wet grasslands for hundreds or thousands of
may not respond if these are already at maximal produc- years as a vital part of the farm economy, coincidentally
tion (Yang et al. 2008). Moreover, enhanced productivity producing highly valued and protected cultural landunder increased precipitation in certain regions (Table 2; scapes such as the English flood meadows, subalpine wet
Ramsar 2002) will alter vegetation composition and struc- pastures and central European wet meadows (Joyce and
ture, potentially reducing nesting and feeding opportuni- Wade 1998). Reduced or unreliable production due to
ties for birds if the sward becomes too dense or tall, climate change represents a challenge to the vestiges of
especially early in the season. Excessive precipitation or these agri-­environmental systems and their cultural heritfloods could shorten flowering duration of grassland spe- age, as these are already considered to be of marginal ecocies (Jentsch et al. 2009) and reduce production by dam- nomic utility (Joyce 2014). The consequence could be the
aging vegetation or inducing community or physiological withdrawal of grazing and cutting management from wet
changes, such as in height, cover, biomass, and species grasslands. This withdrawal would soon alter the ecology
and then lead to the loss of sites that depend upon regular
composition.
extensive agricultural management to maintain their characteristic biodiversity and ecosystem services, including
Human implications
many remaining in Europe and North America. Studies of
Climate change effects on wet grasslands threaten hu- wet grassland abandonment reveal that plant community
man livelihoods in many regions (Table 2) because these changes have been measured within three years, includwetlands are a vital source of income for millions of ing species elimination as competitors expand and woody
Ecosystem Health and Sustainability
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Special Feature: Wetlands and global climate and land-use change
plants encroach (Joyce 2014). Little is known about the
effects of abandonment on other important components
of biodiversity, although invertebrates may eventually decline in unmanaged wet grasslands (Joyce 2014).
Climate change will interact with other human pressures, such as land use and water extraction, such that
stakeholder responses will be vital for wetlands, potentially exacerbating or moderating impacts. For example,
intensifying droughts could lead to negative feedback for
floodplain grasslands if dry conditions provoke greater
water extraction (e.g., for irrigation and municipal purposes) and so reduce water availability for wetlands.
Intensive agricultural management has already led to severe losses of wet grasslands and their biodiversity (Joyce
2014), and climate change represents an emerging threat
to the relatively few diverse sites that have escaped agricultural intensification, for example, in Europe, Australia,
and North America. Agricultural intensification could
also compound climate change effects as the process often incorporates flood defences and/or land drainage, as
well as the use of inorganic fertilizers, herbicides, and
pesticides. Ultimately, such reclaimed areas may be overgrazed or cultivated for crops, reducing their ability to
buffer the impacts of climate change. Agricultural grasslands are more sensitive to climatic variability than natural landscapes because drainage and grazing will typically
reduce water infiltration and increase surface runoff and
pollutant loading (Erwin 2009, Zacharias and Zamparas
2010). Examples of interactions between climate change
and actions of stakeholders that could have detrimental
implications for wet grasslands can be found in Australia
and South America. In northern Australia, increased rainfall and government policy may lead to more dam building, water storage, and drainage schemes, which could
facilitate the conversion of wet grasslands into palm oil
plantations, or other forms of cultivation (Finlayson et al.
2013). In South America, biofuel demand has increased
the pressure on wet grasslands of the Brazilian cerrado
and Argentinian chaco (Junk et al. 2013).
Climate Mitigation and Adaptation
Mitigation here refers to reducing the effects of climate
change, while adaptation describes modifications to policies and practices in response to expected climate
change. The most successful initiatives for wet grasslands are likely to focus upon hydrology, landscape management, and restoration or creation, and integrate
planning, monitoring, and practices (Table 3). Inter­
disciplinary schemes that incorporate the environmental
services that wet grasslands provide, and initiatives that
promote hydrological and ecological resilience to buffer
climate change effects, are emphasized in the following
section.
Integration of climate change mitigation and adaptation
objectives within environmental, and also agricultural,
policies would be particularly beneficial for wet grasslands. Agri-­
environment schemes are key instruments
because they have been implemented in many countries
and generally offer financial incentives to encourage the
types of low-­intensity, low-­input agriculture that produces
the most diverse and important wet grasslands for nature
conservation. Moreover, these schemes can adopt a landscape, catchment, or whole-­farm approach and integrate
conservation objectives (such as raising water levels or
delayed cutting dates to protect nesting birds) with providing a viable income (Glaves 1998). Such schemes could
be adapted to reflect the mitigation priorities of a climate
change future (Table 3), for example, focusing upon hydrological management and wet grassland restoration or
creation to provide ecosystem services such as carbon sequestration and groundwater recharge. Farmers could also
be offered incentives to use hardy, often traditional, breeds
of livestock adapted to climate extremes, or even consider
Table 3. Mitigation and adaptation initiatives (partly after Ramsar 2002) for wet grasslands to combat climate change.
Initiative category
Hydrology
Landscape
Planning and monitoring
Mitigation
Adaptation
Store water at peak periods to counteract
high evaporation rates
Irrigate drought-­afflicted sites
Lower the ground surface to facilitate
­inundation
Desalinate sea water to provide fresh water
Provide corridors and networks of sites to
promote resilience
Assist species movement using seed and
hay transfer
Acquire inland buffer zones to mitigate sea
level rise
Monitor and control invasive species
Retain seed banks
Protect climate-­vulnerable species
Ecosystem Health and Sustainability
11
Address pressures on freshwater supply
Expand water management plans
Set back flood and coastal defences and i­nfrastructure
Restore and create wet grasslands away from
­vulnerable coasts
Focus on climate-­resilient sites and ecosystems
Modify agri-­environment schemes to support climate
mitigation
Utilize climate-­resilient forage species and l­ivestock
breeds
Manipulate disturbance regimes, including ­cutting
dates and grazing
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JOYCE ET AL.
Special Feature: Wetlands and global climate and land-use change
novel grazers for wet grasslands such as water buffalo
(Wiegleb and Krawczynski 2010). The unique properties of
wet grasslands as transitional ecosystems with characteristic vegetation dependent upon human intervention make
them ideal candidates to trial such “agri-­climate” schemes.
An example could be the use of riparian grasslands to buffer impacts of suspended sediments and pollution reaching
rivers due to increased incidence of severe rain events.
Generally, there will be a need for a greater focus on
hydrological functioning, monitoring, and management
of wet grasslands in a climate change future (Table 3).
Water management plans and water budgeting should
therefore assume more importance and widespread
use. The design and maintenance of water control infrastructure, such as drainage channels, bunds, levees, and
sluices, will become even more critical, as it can be used
to drain water from grasslands experiencing extreme
or unseasonal floods or to store water and irrigate dry
wetlands. However, active water-­level monitoring will
be required in order to allow rapid adjustments to be
made, especially due to extreme climate events. It will
be important to maintain inundation in many wet grasslands, as flooding can import seeds or other propagules
and also create gaps in the sward to facilitate establishment. For example, a rapid restoration of abandoned
alluvial meadows in the Czech Republic was likely due
to flood-­borne seeds penetrating the dense vegetation
from sources nearby (Prach et al. 1996). If flooding is absent, raising water levels and reinstating inundation can
be effective for rehabilitating wet grasslands (Toogood
and Joyce 2009). Diverting or pumping water from rivers, reservoirs, or groundwater is likely to be required
for some sites, provided there is sufficient water and it is
of suitable quality. Rehabilitating drought-­affected wet
grasslands could include water storage during the rainy
season, for example, by reservoir construction or using
natural water bodies, so that this can be used to irrigate
the wetland during dry periods (Table 3). In severe cases
where wet grasslands may be subject to extended drying and persistent low water levels, lowering the grassland surface may be an option, as has been attempted in
western Europe using turf and topsoil stripping (Van der
Hoek and Braakhekke 1998, Klimkowska et al. 2007).
Nature conservation will need to adapt to climate
change by prioritising the protection and management of resilient wetlands and adopting more flexible
approaches to management. Resilient wet grasslands
­
are likely to be those with a diversity of plant functional
traits that enhance capacity to resist or tolerate drought
or prolonged inundation (Brotherton and Joyce 2015).
Conservation management should embrace a more flexible rather than overly prescriptive approach given the
increasing climate variability forecast. Cutting dates and
livestock grazing will need to vary in relation to disturbance events (Table 3), notably flooding, and stress such
as drought, in order to maintain a dynamic equilibrium
for optimal diversity and production. Management will
need to be adaptive, and will require flexibility over
stocking densities and perhaps greater use of rotational
grazing. Cutting dates for conserving wet meadows will
need to accommodate changed reproductive phenology under future climates, for example, brought forward
where warming advances maturation so that biomass
does not accumulate and a diversity of species can be
sustained.
Restoration and creation of wet grasslands to combat
climate change should attempt to generate a resilient
network of sites capable of facilitating species survival
at the landscape or regional scale (Table 3). Although
isolated sites can act as refugia or protect against invasion by harmful species, small sites are likely to be more
vulnerable to the detrimental effects of extreme climate
events. Therefore, it is probable that the scale of restoration ­projects will need to increase to consider entire
catchments or substantial landscapes, with an emphasis
on restoring natural functions (e.g., water storage) and
facilitating movement of species (Table 3). For example,
wet grasslands could be restored along floodplains so
that the river system can function as a corridor (Casanova
2015). Restoration cannot often rely upon the seed bank,
however, because many wet grassland seeds are rather
transient (Jensen 1998, Falińska 2000). Also, many typical wet grassland plants, such as sedges, have low colonization efficiency due to limited dispersal ability or
viability following drying (Kettenring and Galatowitsch
2011). Unless a local species pool is readily available,
with a suitable natural vector and receptor environment,
human intervention may be needed for restoration.
Isolated sites and constrained plant species or guilds
(e.g., meadow perennials, rare species) may require particular efforts to ­restore them. Seed transfer, with topsoil
removal and careful ­rewetting, has been recommended
to restore severely d
­ egraded fen meadows (Klimkowska
et al. 2007) while cut hay has been moved between sites
to restore floodplain grasslands (Manchester et al. 1998).
Such techniques could also be used to assist the migration of species threatened by changing climate. Plant
traits can be used in restoration or creation schemes to
design more robust wet grassland systems, capable of
adapting to future climate conditions.
Ecosystem Health and Sustainability
Conclusions
Wet grasslands are at risk from predicted climate changes,
yet these wetlands provide vital ecosystem services, biodiversity, and agricultural and cultural value. These ecosystems have a role to play in mediating some
consequences of climate change, especially wetlands that
are functionally diverse. For climate change planning,
there is a lack of information and focus on wet grasslands
in wetland inventories and mapping, especially for Africa
and the Neotropics, partly due to difficulties to accurately
identify and define these systems. It is evident, however,
that some of the most important wet grassland systems in
12
Volume 2(9) v Article e01240
JOYCE ET AL.
Special Feature: Wetlands and global climate and land-use change
the world are threatened by climate change, including
those in the prairie region of North America, Baltic and
North Sea coastal wetlands in Europe, the South American
flooding pampas, some of the largest flood pulse grasslands in Africa, and extensive deltaic marshes in Asia and
Australia. Consequently, the livelihoods of millions of
people will be affected as climate changes and wet grassland function is threatened.
The ecology of wet grasslands will be fundamentally modified by climate change, especially by altering
hydrology and exposure to extreme climate events.
Scenarios for future wet grasslands under climate change
projections suggest that these wetlands would become
characterized by more variable hydrology, with more
intense disturbance events such as storms and floods.
Wetland productivity would also become more variable,
with increased susceptibility to invasion by woody, non-­
native, and C4 species, and possibly reduced biodiversity.
Consequently, the conservation status and agricultural
value of wet grasslands would be compromised.
Adaptive management strategies for wet grasslands
will be needed to combat climate change. Conservation
and restoration should focus on resilient sites with diverse functional traits and natural ecosystem processes.
Management practices will need to integrate climate effects, for example, by adopting responsive water management, variable cutting dates, and flexible grazing
plans; otherwise, there is a risk that economically marginal wet grasslands will be abandoned (Joyce 2014).
Conservation and management planning should ideally
be on a regional or landscape scale based on expected
specific climate changes, especially water availability,
and adequate monitoring. Thus, flexible and resilient
practices will be required to conserve the biodiversity
and agricultural production of wet grasslands in a climate change future.
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Acknowledgments
Thanks to Don Brown (IWEL Ltd., UK), Professor Peter Gell
(Federation University, Australia), and Dr. Beth Middleton (USGS
Wetland and Aquatic Research Center, United States) for advice on
regional climate change and affected wet grassland systems.
Thanks also to three anonymous reviewers and a subject editor for
comments that greatly improved the manuscript. Fig. 1f was kindly
supplied by Dr. Ray Ward, University of Brighton, UK.
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